@Jonathanglick For now, I think it's populated because subscription Substackers think quite highly of that platform, and are willing to help jumpstart notes with them. Its value might become a victim of success, if it really does become a new Twitter, as the clientele grows less select. But for now it is mostly Substack writers and subscribers (I found myself there via Substack's mailing digests to subscribers), which is imparts a helpful selection bias. /fin